The present invention is an improved steered vehicle, which vehicle be a road vehicle or a vehicle devised to be used both upon road surfaces and also upon a rail line.
Commercial vehicles designed for use upon public roads, quite apart from any actual or potential conflict with cars and other vehicles intended for roadway use, have the major disadvantage of limited manoeuvrability. Transport costs require that such vehicles carry as large a load as possible but, as such vehicles become longer and/or heavier in their design, their ability to cope with existing roadways is diminished. The load may be better distributed by the use of articulated or unarticulated vehicles, including bogies and bogie-trailer combinations, and any resulting increase in vehicle length does not inevitably require more lateral roadway space if a steered bogie is fitted. However current regulations do not reflect these potential design benefits and the legally permitted maximum vehicle length remains restricted. In this situation, only the cheaper fixed axle systems are commercially viable.
Railway transport systems may take much longer vehicles, that is engines and coaches articulated together, and also of course do not impede road vehicle users. However they rely upon installed railway lines, junctions and sidings, which therefore currently make load transport possible only between predetermined locations.
A combined use of road and rail transport currently requires a transfer of the load from one such form of transport to the other, which inevitably entails a delay and also additional costs. There would be very real merit in a vehicle which is itself able to run both on road and rail but of course the transition of that vehicle from a roadway to a rail line entails both a difficult manoeuvre of alignment of the vehicle body and also the critical engagement of rail wheels with the latter line.
Thus road vehicles as such and rail vehicles both have their disadvantages and limitations but a combined road/rail vehicle, while therefore being a desirable aim, introduces very serious problems of itself for resolution. The present invention offers the possibility of overcoming at least some of these various difficulties.